The present invention relates to a system and method for disposing of wastewater from a vehicle, and more particularly, to a system and method for disposing of wastewater from black and gray water holding tanks of a vehicle such that the black water tank and discharge lines are cleaned thoroughly without using fresh water or an excessive amount of gray water.
Recreational vehicles, which includes a variety of motor homes, travel trailers, and campers, are widely used and provide short-term or long-term living quarters. In this regard, a conventional recreational vehicle (RV) typically includes indoor plumbing, which includes a sink, a bathtub or shower, and/or a toilet. Larger RVs typically include multiple sinks, showers, and toilets, and can produce several gallons of wastewater per day, which is typically stored on board and disposed of at regular intervals.
The wastewater in an RV is commonly referred to as either gray water or black water. The gray water is the discharge from the kitchen sink, dish washing water, and water from the bathroom sink and shower. The black water is the water and waste from the toilet. The black water and gray water are stored separately in a black water tank and a gray water tank, respectively, but can be discharged from a common discharge pipe connecting the tanks.
More specifically, the black water tank and gray water tank are connected by a xe2x80x9cYxe2x80x9d connection having a common discharge end. Each tank includes a valve leading to the Y connection so that the tanks can be drained individually. Conventional drainage systems include a single flexible drainage hose that is temporarily connected to the end of the discharge pipe by the RV user for draining the wastewater to a sewer or other storage device. Conventional systems rely on gravity, such that if either tank is opened, the volume in the tank empties out the gravity fed system to the sewer. In an attempt to keep the flexible hose clean, the black water tank is typically drained first followed by the gray water tank. This method appears simple, but it is filthy and unhealthy. For example, the flexible drainage hose can slip off the underground sewage line causing wastewater to spill out on the ground. Even worse, the drainage hose can slip off the drainage pipe and spill raw sewage into a compartment in the RV or on the RV user. If the RV user avoids either of these scenarios, however, the end of a conventional hose remains open, such that after the draining process remnants of the wastewater can drip out of the end of the hose and come in contact with the RV or RV user.
In addition, the RV user must endure the rather unsanitary process of removing and rinsing the drainage hose, such as by using a fresh water hose, and then placing the drainage hose back into the storage compartment where it is kept for future use. This is often avoided by the RV user for obvious sanitary reasons. Under the gravity fed conventional system, the total time required to empty the tanks and rinse the hose and tanks from inside the RV is approximately 25-35 minutes. This process must be repeated two to three times weekly for an average use.
A well-known problem in the RV industry is the clogging of the black water tank and the discharge pipe leading from the black water tank due to solids and other matter becoming clogged in the tank, which results in periodic replacement of the black water tank or extremely unsanitary maintenance and repair of the tank. A major contributor to this problem is in the flushing of the RV toilet, which is different than the flushing of a conventional toilet in that only a small fraction of water is used to flush the toilet compared to a conventional toilet. This is done to conserve fresh water and to limit the volume taken in the black water tank. Because of this, the black water tank has a higher concentration of solid matter, which often leads to clogging the black water tank when emptying the tank. The only way to introduce water to the black water tank is to flush the commode manually as described above, or attach a water hose to a black water tank intake port, which may be either provided by the manufacturer or installed by the RV user. Obviously this requires fresh water, either from the RV fresh water tank or an outside source, which is very wasteful and time consuming.
In addition, it is also known that detergents and surfactants can help break up clogs in the black water tanks. A conventional method to obtain the benefits of detergents and surfactants is to wash dishes in a bucket in the kitchen, and then dump the bucket into the commode to furnish a rinse having detergents and surfactants, which also conserves space in the gray water tank. Due to the tedious steps of hooking up a fresh water hose or taking the time to stand on the flush valve of the commode in order to introduce water to the black water tank, most RV users don""t take time to rinse the black water tank. Thus, the black water tank will settle with solids and cause blockage in the discharge pipe. Accordingly, the black water tank and/or discharge pipe will have to be replaced or repaired, often at great expense.
Another problem with conventional RV disposal systems is the frequency at which the storage tanks must be discharged. Typically, the gray water tank and the black water tank hold the same volume, such as 45 gallons each. The amount of gray water produced is much greater than the black water in common usage. For example, two people typically produce 15 gallons of gray water daily, while black water production is only about 3 gallons per day. Accordingly, a large portion of the space in the black water tank goes unused since there is not currently a crossover to the two tanks due to plumbing codes and the design of conventional plumbing systems. Thus, it is desirable to provide a wastewater disposal system that quickly empties the tanks in a sanitary fashion without using fresh water or requiring inconvenient operations by the RV user. It is also desirable to increase the time between emptying the tanks so the RV user can have a more enjoyable RV experience.
The present invention is directed to a wastewater disposal system for a vehicle, such as a recreational vehicle, that provides a simple, inexpensive method for flushing the gray water and black water tanks in the vehicle. For sanitation and efficiency purposes, the system according to one embodiment of the present invention is permanently attached to the wastewater discharge pipe of a recreational vehicle and provides a pump, such as a macerator pump, for grinding the waste into small pieces before directing the waste out a drainage tube leading to the sewer. Advantageously, the system and method of the present invention allows the gray water from the gray water tank to be directed into the black water tank so that the black water tank and discharge lines can be thoroughly cleaned using the gray water instead of using fresh water. Furthermore, the system and method of the present invention provide a sanitary and efficient way to store wastewater in the recreational vehicle so that the storage capacity is up to twice that of conventional systems.